The present invention relates to a load power controlling apparatus provided for a user of an electric power system, and more particularly to a load power controlling apparatus which can contribute to balance between supply and demand (referred to as supply-demand balance) in the power system.
The power system is based on supply-demand balance of electric power. Usually, an electric power company supplies power and user's or consumers (factories, buildings, homes, etc.) consume it. When the supply-demand balance is lost, the voltage and frequency become unstable, thereby affecting several kinds of electric appliances. Thus, the supply-demand balance must be controlled so as to be as stable as possible.
However, generally, an electric power company is responsible for maintaining the supply-demand balance, whereas users consume the power necessary for them irrespective of the supply-demand balance in an electric power system. The electric power company therefore pays a vast sum of money to maintain the supply-demand balance.
Some users are provided with equipment for limiting the power consumed by themselves. One example is a demand control apparatus disclosed in JP-A-55-155523 (laid open on Dec. 3, 1980).
In recent years, an electric power system has a tendency that load increases in summer to lower the reserve margin of electric power. In the state where the supply reserve margin has been lowered, the electric power company may become unable to control the supply-demand balance.
As described above, the supply-demand balance control in an electric power system is usually the duty of an electric power company, and users consume electric power necessary for themselves without being concerned with the problem of unbalance of supply and demand of the power and reduction in the supply reserve margin. The above demand control apparatus limits power supply when a user consumes an amount exceeding a previously agreed amount of power, but does not entirely consider the supply-demand balance and the supply reserve margin at this time.
Under such a circumstance, the consumers are obliged to consider the problems of the demand-supply balance and the supply reserve margin.